The Rotational Spectroscopy of SrS Kerry C. Etchison, Chris T. Dewberry and Stephen A. Cooke Department of Chemistry, University of North Texas P.O. Box Denton, TX 76203

Introduction Strontium is an alkaline earth metal, silvery white in appearance and has one isotope with nuclear spin. – 87 Sr 7.00% abundant I = 9/2 Strontium Sulfide has been the subject of two previous high resolution studies. –Rotational analysis of the A 1 Σ + -X 1 Σ + transition of SrS F. S. Pianalto, C. R. Brazier, L. C. O'Brien and P. F. Bernath. J. Mol. Spectrosc., 132, 80 (1988) –The pure rotational spectra of SrSH (X 2 A') and SrS (X 1 Σ + ): further studies in alkaline-earth bonding D.T. Halfen, A.J. Apponi, J.M. Thompsen, and L.M. Zuirys J. Chem. Phys., 115, (2001)

Experimental Method

Our Spectrometer

Our Spectrometer Circuit

The Walker-Gerry Ablation Nozzle

The Strontium Rod OCS was used as the precursor gas.

Our Results

Example of what we see: 88 Sr 32 S 350 Avg. Cycles J = 2-1 v = 1 after 548 shots

Summary of data collected Spectra of four isotopomers – 88 Sr 32 S J = 1-0 v = 0, 1, and 2 J = 2-1 v = 0, 1, 2, and 3 J = 3-2 v = 0 and 1 – 87 Sr 32 S J = 2-1 v = 0 J = 3-2 v = 0 – 86 Sr 32 S J = 2-1 v = 0 and 1 J = 3-2 v = 0 – 88 Sr 34 S J 3-2 v = 0

Table of Data Collected

Spectral Analysis For the 87 Sr 32 S isotopomer we used SPFIT for the initial analysis of the data. This was followed by prediction of hypothetical line centers for each v, (J+1) - J transition observed. These line centers together with the rest of the data set and also the data of Halfen, et al. were then used in a Dunham- type analysis.

Three areas to discuss: 1. The quadrupole coupling constants 2. The Dunham analysis 3. The Born-Oppenheimer Breakdown terms in SrS

Quadrupole Coupling Constants eQq ( 87 Sr) 87 Sr 16 O/MHz (37) 87 Sr 32 S/MHz (85)

The Dunham Analysis In our analysis we have followed Watson’s formalism in which:

The Dunham Analysis r e BO (SrS) = (21) Å

Born-Oppenheimer Breakdown Terms AB ∆∆ U01 / u MHz HCl-0.26(20)0.1262(8) (96) CO (12) (24) ZrS-5.325(82)-6.523(39) (19) GeS-1.463(70)-1.871(45) (12) SrS-0.78(30)-3.77(57) (15) A 01 B 01

Conclusions The pure rotational spectra of four isotopomers of SrS have been measured in their electronic ground states on a newly constructed laser ablation, FTMW spectrometer. The quadrupole coupling constant for Sr in SrS has been determined for the first time. A multi-isotopomer analysis has allowed the determination of the Born-Oppenheimer breakdown terms for Sr and S in SrS.

Acknowledgements ACSWC 2007 Travel Grant PRF Type G Ralph E. Powe Junior Faculty Enhancement Award UNT Mech. Workshop

The Cooke Group

The UNT New Chemistry Building